Surge protectors (Surge Protective Devices, SPD) installed in distribution board panels are primarily used to protect electrical equipment from transient voltages (surges or spikes) caused by lightning strikes, power grid fluctuations, or other factors. The truth is, picking the right protection level for distribution boxes isn't just about compliance paperwork—it's about real-world reliability when it matters most. Distribution boxes protect our electrical systems like bodyguards shield VIPs. When they fail, everything goes dark. Today, we'll. The outgoing line from the low-voltage end of the transformer is 0. 4kV to the distribution cabinet (primary distribution cabinet), then the outgoing line is led to the distribution box (secondary distribution box) in each building, and finally the outgoing line is led to the distribution cabinet. Primary distribution systems consist of feeders that deliver power from distribution substations to distribution transformers. A feeder usually begins with a feeder breaker at the distribution substation. Many feeders leave substation in a concrete ducts and are routed to a nearby pole. Depending on the application and protection. ABB's medium voltage switchgear (1 kV to 52 kV according to the IEC standards) are designed to connect and protect an evolving grid.